Diagnostic Ultrasound in Dermatology

Foreword I
Foreword II
Foreword III
Outline
Preface
Contents
List of Editors and Contributors
	Honorary Editor-in-Chief
	Editor-in-Chief
	Associate Editor
	Editor-in-Chief
	Associated Editor
	Contributors
1: Overview of Skin Ultrasound
	1.1	 Development and Overview of Skin Ultrasound
	1.2	 Ultrasound Wave and Ultrasound Imaging
		1.2.1	 Ultrasound Wave
			1.2.1.1	 Basic Concepts
			1.2.1.2	 Physical Properties
		1.2.2	 Propagation Properties
			1.2.2.1	 Acoustic Impedance (Z)
			1.2.2.2	 Reflection, Refraction, and Scattering
			1.2.2.3	 Doppler Effect
			1.2.2.4	 Attenuation
		1.2.3	 Generation and Reception of Ultrasound Waves
			1.2.3.1	 Ultrasound Transducer
			1.2.3.2	 Acoustic Field
			1.2.3.3	 Focusing of Acoustic Beam
		1.2.4	 Resolution of Ultrasound Imaging
			1.2.4.1	 Spatial Resolution
			1.2.4.2	 Temporal Resolution
			1.2.4.3	 Contrast Resolution
		1.2.5	 Basic Principle of Ultrasound Imaging
		1.2.6	 Gray-Scale Ultrasound
		1.2.7	 Color Doppler Flow Imaging
		1.2.8	 Pulse Doppler Imaging
			1.2.8.1	 Baseline
			1.2.8.2	 “Window”
			1.2.8.3	 Frequency Spectrum Bandwidth
			1.2.8.4	 Systolic Peak
			1.2.8.5	 End Diastole
		1.2.9	 Power Doppler Ultrasound
	1.3	 Layout of Examination Room
		1.3.1	 Room Requirement
		1.3.2	 Equipment
		1.3.3	 Materials
		1.3.4	 Disinfection Equipment
	1.4	 Preparation for Examination
		1.4.1	 Preparation
		1.4.2	 Position
		1.4.3	 Selection and Adjustment of Ultrasound Device
			1.4.3.1	 Selection of Ultrasound Device
			1.4.3.2	 Selection, Application of Ultrasound Transducer, and Image Interpretation
				Selection of Ultrasound Transducer
				Utilization of the Ultrasound Transducer and Image Interpretation
			1.4.3.3	 Adjustment of Ultrasound Devices
				Adjustment of Gray-Scale Ultrasound
				Adjustment of Color Doppler Flow Imaging
				Adjustment of Pulse Wave Doppler Imaging
		1.4.4	 Influencing Factors for Skin Ultrasound Imaging
			1.4.4.1	 Pressure
			1.4.4.2	 Hairs
			1.4.4.3	 Wrinkles
			1.4.4.4	 Temperature
			1.4.4.5	 Precautions
	1.5	 Cleaning of Ultrasound Device and Personnel Protection
		1.5.1	 Cleaning of Ultrasound Device
		1.5.2	 Cleaning of Transducer
		1.5.3	 Personnel Protection
	1.6	 New Ultrasound Technology in Skin Ultrasound
		1.6.1	 Extended Field of View
		1.6.2	 Ultrasound Elastography
		1.6.3	 Contrast-Enhanced Ultrasound
		1.6.4	 Three-Dimensional Ultrasound
		1.6.5	 Interventional Ultrasound
		1.6.6	 Artificial Intelligence in Skin Ultrasound
		1.6.7	 Superb Microvascular Imaging
		1.6.8	 Tissue Harmonic Imaging
	1.7	 Indications for Skin Ultrasound
	Suggested Reading
2: Anatomy and Ultrasound Manifestation of Normal Skin
	2.1	 Normal Skin Anatomy
	2.2	 Ultrasound Manifestation of Normal Skin
		2.2.1	 Epidermis and Dermis
		2.2.2	 Skin Appendages
			2.2.2.1	 Nails
			2.2.2.2	 Nerves
			2.2.2.3	 Blood Vessels
		2.2.3	 Subcutaneous Tissue
	2.3	 Training and Suggestions
		2.3.1	 Personnel Training
		2.3.2	 Ultrasound Device
		2.3.3	 Disinfection Materials
		2.3.4	 Image Database
		2.3.5	 Popularization and Communication
		2.3.6	 Skin Ultrasound Examination Reporting
		2.3.7	 Other Suggestions
	Suggested Reading
3: Other Imaging Techniques for Skin
	3.1	 Dermoscopy
	3.2	 Optical Coherence Tomography
	3.3	 Confocal Laser Scanning Microscope
	3.4	 Computed Tomography
	3.5	 Magnetic Resonance Imaging
	3.6	 Comparison of Various Skin Imaging Techniques
	Suggested Reading
4: Terminology, Image Interpretation, and Artifacts for Skin Ultrasound
	4.1	 Terminology and Image Interpretation
		4.1.1	 Gray-Scale Ultrasound
			4.1.1.1	 Ultrasound Features
				Echogenicity
				Layers of Involvement
				Surface
				Bottom
				Stratum Corneum
				Shape
				Internal Composition
				Special Signs
			4.1.1.2	 Measurement
				Size
				Thickness
					Regular Shape
					Crawling
					Irregular Shape
					Ill-Defined Boundary
		4.1.2	 Color Doppler Ultrasound
		4.1.3	 Pulsed Doppler Ultrasound
	4.2	 Artifacts
		4.2.1	 Gray-Scale Ultrasound Artifacts
			4.2.1.1	 Acoustic Shadowing
			4.2.1.2	 Reverberation Artifact
			4.2.1.3	 Side Lobe Artifact
			4.2.1.4	 Partial Volume Effect
			4.2.1.5	 Posterior Acoustic Enhancement
			4.2.1.6	 Mirror Effect
		4.2.2	 Doppler Ultrasound Artifacts
			4.2.2.1	 Color Doppler Signal Overflow
			4.2.2.2	 Color Doppler Twinkling Artifact
			4.2.2.3	 Flash Artifact
			4.2.2.4	 Aliasing Artifact
	Suggested Reading
5: Skin Tumors
	5.1	 Benign Skin Tumors
		5.1.1	 Epidermoid Cyst
			5.1.1.1	 Clinical Manifestation and Pathology
			5.1.1.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.1.3	 Differential Diagnosis
				Trichilemmal Cyst
				Dermoid Cyst
			5.1.1.4	 Diagnosis Clues
		5.1.2	 Digital Mucous Cyst
			5.1.2.1	 Clinical Manifestation and Pathology
			5.1.2.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.2.3	 Differential Diagnosis
				Epidermoid Cyst
				Heberden’s Nodes
			5.1.2.4	 Diagnosis Clues
		5.1.3	 Trichilemmal Cyst
			5.1.3.1	 Clinical Manifestation and Pathology
			5.1.3.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.3.3	 Differential Diagnosis
				Epidermoid Cyst
				Dermoid Cyst
				Pilomatricoma
			5.1.3.4	 Diagnosis Clues
		5.1.4	 Steatocystoma
			5.1.4.1	 Clinical Manifestation and Pathology
			5.1.4.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.4.3	 Differential Diagnosis
				Epidermoid Cyst
				Trichilemmal Cyst
				Dermoid Cyst
			5.1.4.4	 Diagnosis Clues
		5.1.5	 Lipoma
			5.1.5.1	 Clinical Manifestation and Pathology
			5.1.5.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.5.3	 Differential Diagnosis
				Liposarcoma
				Epidermoid Cyst
			5.1.5.4	 Diagnosis Clues
		5.1.6	 Pigmented Nevus
			5.1.6.1	 Clinical Manifestation and Pathology
			5.1.6.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.6.3	 Differential Diagnosis
				Seborrheic Keratosis (SK)
				Malignant Melanoma (MM)
			5.1.6.4	 Diagnosis Clues
			5.1.6.5	 Clinical Significance
		5.1.7	 Seborrheic Keratosis
			5.1.7.1	 Clinical Manifestation and Pathology
			5.1.7.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.7.3	 Differential Diagnosis
				Actinic Keratosis (AK)
				Basal Cell Carcinoma (BCC)
				Bowen’s Disease (BD)
			5.1.7.4	 Diagnosis Clues
		5.1.8	 Pilomatricoma
			5.1.8.1	 Clinical Manifestation and Pathology
			5.1.8.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.8.3	 Differential Diagnosis
				Superficial Lymph Node
				Epidermoid Cyst
				Hemangioma with Calcification
			5.1.8.4	 Diagnosis Clues
		5.1.9	 Scar
			5.1.9.1	 Clinical Manifestation and Pathology
			5.1.9.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.9.3	 Differential Diagnosis
			5.1.9.4	 Diagnosis Clues
			5.1.9.5	 Clinical Significance
		5.1.10	 Keratoacanthoma
			5.1.10.1	 Clinical Manifestation and Pathology
			5.1.10.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.10.3	 Differential Diagnosis
				Squamous Cell Carcinoma (SCC)
				Nodular Basal Cell Carcinoma (BCC)
			5.1.10.4	 Diagnosis Clues
		5.1.11	 Dermatofibroma
			5.1.11.1	 Clinical Manifestation and Pathology
			5.1.11.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.11.3	 Differential Diagnosis
				Dermatofibrosarcoma Protuberans (DFSP)
				Cavernous Hemangioma
				Verrucous Epidermal Nevus
			5.1.11.4	 Diagnosis Clues
		5.1.12	 Neurofibroma (Neurofibromatosis)
			5.1.12.1	 Clinical Manifestation and Pathology
			5.1.12.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.12.3	 Differential Diagnosis
				Schwannoma
				Hemangioma
			5.1.12.4	 Diagnosis Clues
		5.1.13	 Schwannoma
			5.1.13.1	 Clinical Manifestation and Pathology
			5.1.13.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.13.3	 Differential Diagnosis
				Neurofibroma
				Superficial Lymph Node
			5.1.13.4	 Diagnosis Clues
		5.1.14	 Angioleiomyoma
			5.1.14.1	 Clinical Manifestation and Pathology
			5.1.14.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.14.3	 Differential Diagnosis
				Glomus Tumor
				Epidermoid Cyst
			5.1.14.4	 Diagnosis Clues
		5.1.15	 Poroma
			5.1.15.1	 Clinical Manifestation and Pathology
			5.1.15.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.15.3	 Differential Diagnosis
				Porocarcinoma
				Nodular Basal Cell Carcinoma (BCC)
				Seborrheic Keratosis (SK)
			5.1.15.4	 Diagnosis Clues
		5.1.16	 Abdominal Wall Endometriosis
			5.1.16.1	 Clinical Manifestation and Pathology
			5.1.16.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.16.3	 Differential Diagnosis
				Abdominal Incisional Hernia
				Scar at Abdominal Incision
				Hematoma under Abdominal Incision
			5.1.16.4	 Diagnosis Clues
		5.1.17	 Glomus Tumor
			5.1.17.1	 Clinical Manifestation and Pathology
			5.1.17.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.1.17.3	 Differential Diagnosis
				Nail Papilloma
				Nevi of the Nail Matrix
			5.1.17.4	 Diagnosis Clues
	5.2	 Precancerous Skin Tumors
		5.2.1	 Actinic Keratosis
			5.2.1.1	 Clinical Manifestation and Pathology
			5.2.1.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.2.1.3	 Differential Diagnosis
				SK
				BD
				Superficial BCC
			5.2.1.4	 Diagnosis Clues
			5.2.1.5	 Clinical Significance
		5.2.2	 Leukoplakia
	5.3	 Malignant Skin Tumors
		5.3.1	 Bowen’s Disease
			5.3.1.1	 Clinical Manifestation and Pathology
			5.3.1.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.1.3	 Differential Diagnosis
				Superficial Basal Cell Carcinoma (Superficial BCC)
				AK
				SK
			5.3.1.4	 Diagnosis Clues
			5.3.1.5	 Clinical Significance
		5.3.2	 Basal Cell Carcinoma
			5.3.2.1	 Clinical Manifestation and Pathology
			5.3.2.2	 Ultrasound Manifestation
				Nodular BCC
				Superficial BCC
				Pigmented BCC
				Morpheaform BCC
			5.3.2.3	 Differential Diagnosis
				Malignant Melanoma (MM)
				Cutaneous Squamous Cell Carcinoma (cSCC)
			5.3.2.4	 Diagnosis Clues
			5.3.2.5	 Clinical Significance
		5.3.3	 Cutaneous Squamous Cell Carcinoma
			5.3.3.1	 Clinical Manifestation and Pathology
			5.3.3.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.3.3	 Differential Diagnosis
				Malignant Melanoma (MM)
				BCC
			5.3.3.4	 Diagnosis Clues
			5.3.3.5	 Clinical Significance
		5.3.4	 Malignant Melanoma
			5.3.4.1	 Clinical Manifestation and Pathology
			5.3.4.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.4.3	 Differential Diagnosis
				Melanocytic Nevus
				Hemangioma
				cSCC
			5.3.4.4	 Diagnosis Clues
			5.3.4.5	 Clinical Significance
		5.3.5	 Extramammary Paget’s Disease
			5.3.5.1	 Clinical Manifestation and Pathology
			5.3.5.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.5.3	 Differential Diagnosis
				BD
				MM
			5.3.5.4	 Diagnosis Clues
			5.3.5.5	 Clinical Significance
		5.3.6	 Dermatofibrosarcoma Protuberans
			5.3.6.1	 Clinical Manifestation and Pathology
			5.3.6.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.6.3	 Differential Diagnosis
				Lipoma
				Keloid
				Nodular Panniculitis
			5.3.6.4	 Diagnosis Clues
		5.3.7	 Porocarcinoma
			5.3.7.1	 Clinical Manifestation and Pathology
			5.3.7.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.7.3	 Differential Diagnosis
				Eccrine Poroma
				cSCC
			5.3.7.4	 Diagnosis Clues
		5.3.8	 Sebaceous Gland Carcinoma
			5.3.8.1	 Clinical Manifestation and Pathology
			5.3.8.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.8.3	 Differential Diagnosis
				Nodular BCC
				cSCC
				Nevus Sebaceus
			5.3.8.4	 Diagnosis Clues
			5.3.8.5	 Clinical Significance
		5.3.9	 Trichilemmal Carcinoma
			5.3.9.1	 Clinical Manifestation and Pathology
			5.3.9.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.9.3	 Differential Diagnosis
				cSCC
				KA
			5.3.9.4	 Diagnosis Clues
		5.3.10	 Mycosis Fungoides
			5.3.10.1	 Clinical Manifestation and Pathology
			5.3.10.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.10.3	 Differential Diagnosis
				Eczema
				Psoriasis
			5.3.10.4	 Diagnosis Clues
			5.3.10.5	 Clinical Significance
		5.3.11	 Cutaneous Metastatic Carcinoma
			5.3.11.1	 Clinical Manifestation and Pathology
			5.3.11.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.3.11.3	 Differential Diagnosis
				Herpes Zoster
				Hemangioma
			5.3.11.4	 Diagnosis Clues
		5.3.12	 Lymph Node Metastasis
			5.3.12.1	 Clinical Manifestation and Pathology
			5.3.12.2	 Ultrasound Manifestation (Fig. 5.78)
			5.3.12.3	 Differential Diagnosis
				Normal Lymph Nodes (Fig. 5.79)
				Malignant Lymphoma
				Reactive Lymph Node Hyperplasia
			5.3.12.4	 Diagnosis Clues
	5.4	 Hemangioma and Congenital Vascular Malformation
		5.4.1	 Hemangioma
			5.4.1.1	 Clinical Manifestation and Pathology
			5.4.1.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.4.1.3	 Differential Diagnosis
				Giant Cell Tumor of Tendon Sheath
				Schwannoma
				Epidermoid Cyst
			5.4.1.4	 Diagnosis Clues
		5.4.2	 Port Wine Stains
			5.4.2.1	 Clinical Manifestation and Pathology
			5.4.2.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			5.4.2.3	 Differential Diagnosis
				Infantile Hemangioma
			5.4.2.4	 Diagnosis Clues
	5.5	 Summary
		5.5.1	 Summary of Benign Skin Tumors
		5.5.2	 Summary of Malignant Skin Tumors
		5.5.3	 Diagnostic Clues of Common Skin Tumors
	Suggested Reading
6: Non-tumorous Skin Lesions
	6.1	 Inflammatory Skin Diseases
		6.1.1	 Cutaneous Edema
			6.1.1.1	 Clinical Manifestation and Pathology
			6.1.1.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
			6.1.1.3	 Differential Diagnosis
				Lymphangitis and Erysipelas
				Etiological Identification
			6.1.1.4	 Diagnosis Clues
		6.1.2	 Panniculitis
			6.1.2.1	 Clinical Manifestation and Pathology
			6.1.2.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.2.3	 Differential Diagnosis
				Superficial Lipoma
				Nodular Fasciitis
			6.1.2.4	 Diagnosis Clues
		6.1.3	 Folliculitis
			6.1.3.1	 Clinical Manifestation and Pathology
			6.1.3.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.3.3	 Differential Diagnosis
				Cellulitis
			6.1.3.4	 Diagnosis Clues
		6.1.4	 Cellulitis
			6.1.4.1	 Clinical Manifestation and Pathology
			6.1.4.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.4.3	 Differential Diagnosis
			6.1.4.4	 Diagnosis Clues
		6.1.5	 Wart
			6.1.5.1	 Clinical Manifestation and Pathology
			6.1.5.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.5.3	 Differential Diagnosis
				AK
				SK
			6.1.5.4	 Diagnosis Clues
		6.1.6	 Nodular Fasciitis
			6.1.6.1	 Clinical Manifestation and Pathology
			6.1.6.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.6.3	 Differential Diagnosis
				Superficial Lipoma
				Epidermoid Cyst
				Panniculitis
			6.1.6.4	 Diagnosis Clues
		6.1.7	 Scleroderma
			6.1.7.1	 Clinical Manifestation and Pathology
			6.1.7.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
				SWE
			6.1.7.3	 Differential Diagnosis
				Eosinophilic Fasciitis
				Scleredema Adultorum of Buschke
			6.1.7.4	 Diagnosis Clues
		6.1.8	 Cutaneous Lupus Erythematosus
			6.1.8.1	 Clinical Manifestation and Pathology
			6.1.8.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.8.3	 Differential Diagnosis
				Psoriasis Vulgaris
				Dermatomyositis
			6.1.8.4	 Diagnosis Clues
		6.1.9	 Dermatomyositis
			6.1.9.1	 Clinical Manifestation and Pathology
			6.1.9.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.9.3	 Differential Diagnosis
				CLE
				Solar Dermatitis
			6.1.9.4	 Diagnosis Clues
		6.1.10	 Radiodermatitis
			6.1.10.1	 Clinical Manifestation and Pathology
			6.1.10.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.10.3	 Differential Diagnosis
				Paget’s Disease of the Breast
			6.1.10.4	 Diagnosis Clues
		6.1.11	 Odontogenic Cutaneous Fistula
			6.1.11.1	 Clinical Manifestation and Pathology
			6.1.11.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.11.3	 Differential Diagnosis
				Epidermoid Cyst
				Skin Abscess
			6.1.11.4	 Diagnosis Clues
			6.1.11.5	 Clinical Significance
		6.1.12	 Pseudocyst of the Auricle
			6.1.12.1	 Clinical Manifestation and Pathology
			6.1.12.2	 Ultrasound Manifestation
				Gray-Scale Ultrasound
				Color Doppler Ultrasound
			6.1.12.3	 Differential Diagnosis
				Epidermoid Cyst
				Gouty Tophi
			6.1.12.4	 Diagnosis Clues
	6.2	 Foreign Bodies
		6.2.1	 Clinical Manifestation and Pathology
		6.2.2	 Ultrasound Manifestation
			6.2.2.1	 Gray-Scale Ultrasound
			6.2.2.2	 Color Doppler Ultrasound
		6.2.3	 Differential Diagnosis
			6.2.3.1	 Skin Tumor
			6.2.3.2	 Erysipelas
		6.2.4	 Diagnosis Clues
	6.3	 Psoriasis and Psoriatic Arthritis
		6.3.1	 Clinical Manifestation and Pathology
			6.3.1.1	 Psoriasis Vulgaris
			6.3.1.2	 Psoriasis Pustular
			6.3.1.3	 Erythrodermic Psoriasis
			6.3.1.4	 Arthropathic Psoriasis
		6.3.2	 Ultrasound Manifestation
			6.3.2.1	 Psoriasis Vulgaris
		6.3.3	 Pustular Psoriasis and Erythrodermic Psoriasis
			6.3.3.1	 Psoriatic Arthropathy (PsA)
		6.3.4	 Differential Diagnosis
			6.3.4.1	 Seborrheic Dermatitis
			6.3.4.2	 Gouty Arthritis
			6.3.4.3	 Rheumatoid Arthritis (RA)
		6.3.5	 Diagnosis Clues
	6.4	 Gouty Arthritis
		6.4.1	 Clinical Manifestation and Pathology
		6.4.2	 High-Frequency Ultrasound
			6.4.2.1	 Gray-Scale Ultrasound
			6.4.2.2	 Color Doppler Ultrasound
		6.4.3	 Differential Diagnosis
			6.4.3.1	 RA
			6.4.3.2	 Osteoarthritis
		6.4.4	 Diagnosis Clues
		6.4.5	 Clinical Significance
	6.5	 Summary
	Suggested Reading
7: Skin Aging and Plastic Surgery
	7.1	 Skin Aging
	7.2	 Plastic Surgery
	Suggested Reading
8: Future Development
	8.1	 New Diagnosis and Treatment Mode
	8.2	 Future Prospects
		8.2.1	 I. Ultrafast Ultrasound Localization Microscopy for Deep Super-Resolution Imaging
		8.2.2	 II. Stretchable Ultrasound Transducer
		8.2.3	 III. Automatic Scanning with the Aid of AI
		8.2.4	 IV. Progress of Skin Photoacoustic Imaging
	Suggested Reading
Appendix
	Appendix A: Template of Reports for Skin Ultrasound
	Appendix B: Template of Application Form for Skin Ultrasound